mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-24 18:21:15 +01:00
2540070fd4
Documents that `BikeshedIntrinsicFrom` models transmute-via-union, which is slightly more expressive than the transmute-via-cast implemented by `transmute_copy`. Additionally, we provide an implementation of transmute-via-union as a method on the `BikeshedIntrinsicFrom` trait with additional documentation on the boundary between trait invariants and caller obligations. Whether or not transmute-via-union is the right kind of transmute to model remains up for discussion [1]. Regardless, it seems wise to document the present behavior. [1] https://rust-lang.zulipchat.com/#narrow/stream/216762-project-safe-transmute/topic/What.20'kind'.20of.20transmute.20to.20model.3F/near/426331967
23 lines
557 B
Diff
23 lines
557 B
Diff
- // MIR for `transmute_ref_dst` before LowerIntrinsics
|
|
+ // MIR for `transmute_ref_dst` after LowerIntrinsics
|
|
|
|
fn transmute_ref_dst(_1: &T) -> *const T {
|
|
debug u => _1;
|
|
let mut _0: *const T;
|
|
let mut _2: &T;
|
|
|
|
bb0: {
|
|
StorageLive(_2);
|
|
_2 = copy _1;
|
|
- _0 = std::intrinsics::transmute::<&T, *const T>(move _2) -> [return: bb1, unwind unreachable];
|
|
+ _0 = move _2 as *const T (Transmute);
|
|
+ goto -> bb1;
|
|
}
|
|
|
|
bb1: {
|
|
StorageDead(_2);
|
|
return;
|
|
}
|
|
}
|
|
|